Effect of bismuth (Bi3+) substitution on structural, optical, dielectric and magnetic nature of La2CoMnO6 double perovskite

Abstract

Double perovskite oxide materials represented as A2BB′O6 have attracted a great attention due to their diverse electrical, magnetic and structural properties. In this report, we discuss synthesis, structural, optical, magnetic and electric nature of the double perovskite manganites of the type La2−xBixCoMnO6 [x = 0.0, 0.1, 0.2]. These solid-state reaction route products with x = 0.0, 0.1 were found monoclinic structured (P 1 21 / n 1) confirmed from the X-ray diffraction data analysis, whereas the sample with x = 0.2 has acquired a new structure confirmed to be cubic (Fm-3 m) with another phase corresponding to Bi2O3 crystallized in monoclinic structure acquiring space groups P 1 21 / c 1. The results of XRD data analysis were re-verified via Rietveld refinement. The phase formation was further verified via Raman and FTIR spectral studies. The samples were investigated for composition and morphology also. The optical bandgap was determined (≈ 1 eV) from the diffuse reflectance UV–Vis spectra. Temperature-dependent dielectric constant and dielectric loss was investigated in the temperature range of 320–90 K at various constant values of applied ac field and the results were exceptionally good. Electrical (dc) resistivity exploiting four-probe technique with and without magnetic field infer the samples are semiconducting in nature. Room temperature magnetic measurement reveals the samples exhibit low magnetic moment which shows linear behaviour in both forward and reverse field values.